The present invention relates in general to combined irrigation and drainage systems for irrigating and draining cultivated fields or croplands as conditions require, and more particularly to subsurface irrigation and drainage systems for cultivated fields or croplands of varying topography wherein a network of distribution boxes to which water is supplied to predetermined levels from a head tank supply or receive water to or from a system of two-way subsurface conduits to maintain proper moisture conditions in the soil.
Heretofore, various systems have been proposed for irrigating large area cultivated fields or croplands, some of which have involved open irrigation or drainage ditches arranged in various arrays or networks through the cropland or cultivation area to be served, and which are supplied with water from a higher elevation source, but such systems are subject to extensive loss of water through evaporation, they constitute highly undesirable obstacles for cultivating machinery, and are difficult to achieve appropriate distribution of water throughout the cultivated land area where substantial variations in terrain occur. Surface irrigation systems involving networks of surface or above surface pipes and spraying nozzles have also been used, but such systems involve high operating expense and the use of complicated spraying equipment, and also are difficult to properly operate on highly irregular terrain.
Subsurface irrigation systems formed of networks of apertured pipes have also been proposed before, but have largely relied upon manually adjusted valves at various locations to regulate the supply of water to various branch sections or strings of subsurface irrigation pipe and have not provided for drainage of water from the soil into the pipe system to distribution boxes with excess water communication systems between the distribution boxes when the natural water table rises above the subsurface conduit or pipe system.
An object of the present invention is the provision of a novel irrigation and drainage system for croplands or cultivated land of various topography characteristics, wherein a subsurface system or network of submerged two-way slotted or apertured conduits are connected to a plurality of distribution boxes which are interconnected to provide for flow of supply water or excess water between the various distribution boxes, and having means for maintaining selected water levels in each of the distribution boxes in a manner causing supply of water to the cultivated field or cropland area when the natural water table is below selected levels and causing excess water to be drained from the soil through the conduits to the distribution boxes when the natural water table is above selected levels.
Another object of the present invention is the provision of a novel subsurface irrigation and drainage system for cultivated fields or croplands wherein water from a head tank or similar supply source is supplied through a plurality of interconnected distribution boxes having adjustable weirs therein and connected to two-way submerged perforated conduit strings or branches, together with supply water and excess water conduits interconnecting the distribution boxes and to a water collection or storage facility, providing automatically controlled supply of water for irrigating the cultivated field when the natural water table is below selected levels and for draining water from the field when the natural water table is above selected levels.
Another object of the present invention is the provision of a novel subsurface irrigation and drainage system as defined in the immediately preceding paragraph, wherein the distribution boxes are provided with float control valves for automatically regulating water supply from the head tank or source to maintain a selected water level in each distribution box, and wherein the weir means subdivides the distribution box to provide for excess water drainage to other distribution boxes into the system or to the collection and storage facility.
Other objects, advantages and capabilities of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying description described in preferred embodiments of the invention.